Since organopolysiloxanes (hereinafter sometimes referred to as “silicones”) have many features such as low surface tension, excellent lubricating property and mold releasing property, high thermal stability, generally very low glass transition points, and excellent gas permeability, silicones in various forms are very widely used as lubricants, heat medium, electric insulators, paint leveling agents, mold releasing agents, cosmetic additives, textile treating agents, shock buffering materials, sealing materials, molding materials, polishing agents, foam stabilizers, and defoaming agents.
The cosmetic field is no exception, and silicones are often used as feel improving agents or the like in cosmetic products such as skin care agents, foundations, shampoos, and conditioners. As an example of silicones that can be used in cosmetics, organopolysiloxanes that do not break or are not plastically deformed at extension rates in the range of 0 to 15% at a temperature of 20° C. and a relative humidity of 65% have been disclosed in JP-A-07-133352. Hair cosmetics containing these organopolysiloxanes have excellent hair setting ability and set holding performance, can impart a favorable feel such as flexibility and no stiffness to the hair after setting, and can be easily washed off by shampooing the hair. Thus, the organopolysiloxanes described in JP-A-07-133352 were superior to conventional set polymers.
In recent years, however, required performance and preference in hair cosmetics have been greatly changed, and conventional set polymers or silicones cannot adequately respond to them. Specifically, hair cosmetics are required to impart a flexible feel, have set characteristics that the hair style is not disintegrated after passing fingers through the hair, and, in addition, achieve a more natural finish.
Meanwhile, it is said that chemical treatment with hair color or the like and physical treatment such as blowing cause abrasion of cuticles on the hair surface and hollowing of the hair due to the leakage of lipids from the inside of the hair, resulting in overly dry hair, uneasy finger passing, poor hair manageability, and loss of luster.
To impart manageability to the hair and prevent overly dry hair, hair cosmetics mainly used at present include waxes, emulsified products such as hair creams containing oil solutions such as a higher alcohol, a surfactant, and the like, gels containing a membrane formation polymer (set polymer), and so forth. Such hair cosmetics attach oils and fats or polymers to the hair surface to solve problems such as poor manageability and overly dry hair only temporarily, but could not achieve essential improvement.
Several hair cosmetics for reforming the hair are known, and some of these use specific organic acids and organic solvents for reforming the hair by acting on the inside of the hair. However, while such hair cosmetics have excellent reforming effects to improve luster and manageability of the hair, they suffer from such problems that flexibility is hard to impart, the applied hair becomes greasy, and so forth. Therefore, common silicones are mixed as feel improving agents. However, although the feel to the touch is improved, a problem arises that hair reforming effects (improvement of manageability, etc.) by organic acids and organic solvents are impaired.
To solve such problems, a hair cosmetic has been proposed in which an organopolysiloxane having a specific structure is used in combination with a specific organic acid and a specific organic solvent (JP-A-2006-69899).
Furthermore, due to diversified and individualized hair styles in recent years, hair cosmetics are desired wherein a desired hair style can be easily set, the set hair style can be held for a long time, and a flexible feel and a more natural finish can be imparted. While the above-mentioned hair cosmetic of JP-A-2006-69899 can impart a favorable feel (softness, no greasiness, etc.) without impairing hair reforming effects (improvement of manageability, etc.), neither of styling properties, setting performance and set holding performance, is necessarily adequate, and these properties have room to improve.
JP-A-07-133352
JP-A-2006-69899